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An aircraft seat may appear quite simple, but do not be fooled. Aeronautical standards and the required certifications are very restrictive and impose specific process and material choices. With the aid of designers and developers, every effort is made to guarantee the comfort and safety of the passenger. Here we take an overview with a composites manufacturer that specializes in the domain.
(Published on March - April 2008 – JEC Magazine #39)
The Duqueine Group comprises 3 production sites, with two in France (Duqueine Rhône-Alpes near Lyon, Duqueine Atlantic near Nantes) and one in Romania (Duqueine Romania near Timisoara), and has developed a comprehensive and specific activity in the manufacturing of composite sub-assemblies for aircraft interiors. The company was already an “aeronautical” manufacturer, producing engine test stand equipment (bellmouth, slave fan ducts), air ducting and structural parts. It wanted to broaden its portfolio for the aeronautical market by working on recurrent parts: interior fittings and, more specifically, composite seat shells. This activity was launched in 2004 with the first class seat shell programmes for EADS Sogerma, for the Boeing 747 and 777 and the Airbus A330 and A340. The airlines concerned by these first programmes were Korean Airlines and Gulf Air.
In general, an airline calls in an equipment manufacturer and/or designer for the design and manufacture of its interior cabin fittings. It is the latter’s job to design a complete product for which the elements that fall outside of their own field of competence are subcontracted to a specialist subcontractor. This is very often the case with composite parts. The subcontractor must then determine the best process/ material combination for the manufacture of the parts. However, working methods evolve and the specialist subcontractors are involved at an increasingly early stage in the design of parts, in order to determine the shapes, processes and materials best suited to the objective of reducing the R&D time and the associated R&D and manufacturing costs. Recently, Duqueine took part in numerous design stages at Sicma Aero Seat for the design of the business class seats for the Ryokou and Skylounge programmes. Duqueine is also capable of handling every stage of a seat’s design, and in particular the finite element analysis steps (ILA, abuse loads, flight loads) and real-world testing (static, dynamic, cyclical tests). Hence Duqueine may – depending on the programme – be commissioned simply to manufacture parts, or else to design, dimension and manufacture them. For the latter case, the client supplies simply the aesthetic forms, mechanical constraints and points of interface with the aircraft.
For this activity, Duqueine has developed skills in the processing of phenolic resins, recommended for their excellent fire performance (heat release, fire, smoke, toxicity), which is a sine qua non when it comes to aeronautical certifications for interior fittings. The parts are mostly manufactured using monolithic or sandwich structures made of glass/phenolic prepreg skins and a Nomex core. These parts are then fitted with a multitude of accessories: inserts, sockets, brackets, etc. What is more, every design and production stage is managed numerically.
The technical drawings (parts and tools) are produced on Catia V5. The use of a composite design module makes it possible to define the shapes of the parts and the ply stacking sequences, and to transfer all this data directly to the numerically-controlled cutting machines. The hand lay-up of the parts is done on composite moulds (high temperature carbon/epoxy) with very low thermal inertia, enabling better control of the cure temperatures and optimised cycle times (oven or autoclave).
Duqueine has also developed special techniques to reduce the finishing times: use of Laminat skins (pre-cured plies) on simple curve sandwich structures, application of edging resin on sandwich structures prior to curing, trimming of parts on a 3- or 5-axis numerically-controlled machine, etc. The use of thermoplastic materials (PPS, PEI) is another innovation for this activity, offering the characteristics of very short processing cycle times, excellent fire-resistant properties and mechanical properties significantly superior to those of phenolics, for lighter structures with no loss of mechanical properties.
The key success factors
Change management is a recurrent and delicate matter in this type of market. Responsiveness is therefore very important. The customer often has changes made to his product in the course of the programme in order to adapt to different environments (different aircraft) and to the customization desires of the end customer. A seat "from the catalogue", therefore, may come in practically as many versions as there are customers for it over its life time. Also, the shortening of lead times is another important factor in the aeronautical sector. For example, one of the latest contracts for Sicma Aero Seat, for its business-class seats, was discharged in just 8 months. Finally, as in any industry, innovation and cost reduction are highly important. Besides the examples already cited, Duqueine has developed the MFP patent for Prepreg Bundle Compression technology.
This is a type of compression moulding for producing parts with complex geometries and high-spec mechanical characteristics for very low production costs (very low discard rate, little or no manual operation). This process is particularly suited to mechanical parts that are often made from metallic materials, such as handles, elbow rests and brackets.
The “aircraft interiors” activity of Duqueine is now spread across its 3 production sites (Lyons, Nantes, Timisoara) and involves some 70 people (out of a total headcount of 300). Since it began in 2004, this activity has generated turnover in excess of 5.5 million euros for the sale of "composite shell" products. Around 700 seat shells have already been produced, and the programmes to come with Sicma Aero Seat (Zodiac Group) and EADS Sogerma on the A380 and B787 programmes will more than double these revenues in the space of 2 years. With the trend being towards the integration and reduction of the number of suppliers, Duqueine is looking to leverage its “mass manufacturing” skills, acquired in the manufacture of sports & leisure components (40,000 carbon bicycle wheels per year, the world’s number one manufacturer), to work on programmes for economy class seating.